Airy's Great Equatorial, Greenwich, London, 1914.
© Science Museum / Science & Society Picture Library
Photograph of the Airy's 'Great Equatorial', a 28-inch refracting telescope at the Royal Observatory, Greenwich. Sir Howard Grubb of Dublin built this telescope in 1893 using an earlier mounting made by Ramsome & Sims of Ipswich in England. The telescope was installed in an observatory building that had previous housed a 12-inch refracting telescope. Due to its considerable larger dimensions the existing cylindrical dome was replaced with one with a bulbous form. Known as the onion dome, this has become the observatory's trademark that now forms part of the National Maritime Museum. Despite its age, Airy's 'Great Equatorial' remains the largest refracting telescope in England.